The goal of this research program is to obtain an understanding of the enzymatic generation of singlet oxygen in the body and of the resultant pathological damage that this reactive species may induce. With this fundamental knowledge, specific recommendations for anticancer agents and chemotherapeutic compounds should be possible. The role of singlet molecular oxygen (1O2) and of the superoxide anion radical (O2) in enzyme-mediated peroxidation reactions in vivo has been under investigation. We recently reported that 1O2 is produced by the adrenodoxin reductase system. Singlet oxygen is formed by the dismutation reaction of superoxide anion radicals. Superoxide dismutase (SOD), a metalloprotein containing 2 g-atoms of Cu and Zn each, catalyzes the dismutation reaction of O2 to give ground state molecular oxygen. It is thought that SOD may serve to protect biological systems from the deleterious effects of the highly reactive O2. The mechanism of the reaction of bis-(salicylato)-copper(II) with superoxide anion has been studied in detail by electron paramagnetic resonance and polarography. This copper exhibits dismutation activity in scavenging superoxide. It is possible that this and similar compounds may be potentially useful in preventing oxidative damage in singlet oxygen and superoxide in biological systems. The application of these results in the development of anticancer agents will be pursued.